SOCIAL BEHAVIOR:
Heck's macaque has a multimale-multifemale social system. Females remain in their natal group with the onset of maturity, but males will disperse shortly before adolescence. There is a hierarchical system amongst group members based upon the matriline.

VOCAL COMMUNICATION:scream calls: This call is given by Heck's macaque when they are approached by a non-group conspecific.

OLFACTORY COMMUNICATION:

VISUAL COMMUNICATION:fear grimace: The lips are retracted so that the teeth are shown; the teeth are clenched together (Estes, 1991). This display functions as an appeasement signal to reduce aggression in aggressive encounters (Estes, 1991).

staring with open mouth: This is the stare accompanied by the mouth being open but the teeth are covered (Estes, 1991). This is a threat expression (Estes, 1991).